1. Field of the Invention
The invention relates to a bearing ball for a coupling pin on an agricultural implement for connecting the implement to the three-point connecting device or hitch of a tractor, which ball is designed as a hollow member into which a cylindrical tube which may be attached to the coupling pin is inserted, the bearing ball, in the coupled condition, being accommodated in the hook jaw of a hook belonging to the three-point connecting device.
2. Description of Prior Art
In one prior art bearing ball (DE-PS No. 29 22 716) the two ends of the cylindrical tube are connected to the catching ball by outturned end portions of the tube. The outturning of the tube ensures a firm connection between the hollow ball and the cylindrical tube. In cases where connection is effected by means of a pin, the hollow ball is provided with a cylindrical extension through which the cylindrical tube passes, with both parts being provided with a transverse bore for inserting the pin. The disadvantage of this design is that, on the one hand, as a result of the outturned ends provided on both sides and the continuous design of the cylindrical tube, bending of the implement pin after the bearing ball has been fitted with the cylindrical tube, results in separation forces which act on the bearing ball and adversely influence or destroy the connection between the bearing ball and the cylindrical tube. Furthermore, as a result of the close connection between the hollow bearing ball and the cylindrical tube, any relative movements between the coupling hook accommodating the bearing ball and the outer face of the bearing ball cause wear to occur essentially in the region of the outer face of the bearing ball and of the locking pin of the coupling hook. In consequence, there is a risk that such wear may result in a greater play, as a result of which the locking function would not be permanently ensured.